In Example 1, the probability that the second ball is green is
whether or not the first ball is green. Since the probability that
the second ball is green does not depend on the color of the first
ball, the two events “second ball is green” and “first ball is
green” are called independent events. This is not the case,
however, in Example 2 where the probability that the second ball is
green does depend on whether or not the first ball is green.